Observations of $\Lambda_b^0 \to \Lambda K^+\pi^-$ and $\Lambda_b^0 \to \Lambda K^+K^-$ decays and searches for other $\Lambda_b^0$ and $\Xi_b^0$ decays to $\Lambda h^+h^{\prime -}$ final states

Information

LHCb-PAPER-2016-004
CERN-EP-2016-038
arXiv:1603.00413 [PDF]

(Submitted on 01 Mar 2016)
JHEP 05 (2016) 081
Inspire 1425547

Tools

Abstract

A search is performed for the charmless three-body decays of the $\Lambda_b^0$ and $\Xi_b^0$ baryons to the final states $\Lambda h^+h^{\prime -}$, where $h^{(\prime)} = \pi$ or $K$. The analysis is based on a data sample, corresponding to an integrated luminosity of $3 \rm fb^{-1}$ of $pp$ collisions, collected by the LHCb experiment. The $\Lambda_b^0 \to \Lambda K^+\pi^-$ and $\Lambda_b^0 \to \Lambda K^+K^-$ decays are observed for the first time and their branching fractions and $CP$ asymmetry parameters are measured. Evidence is seen for the $\Lambda_b^0 \to \Lambda \pi^+\pi^-$ decay and limits are set on the branching fractions of $\Xi_b^0$ baryon decays to the $\Lambda h^+h^{\prime -}$ final states.

Figures and captions

Results of the fit for the (left) $\Lambda ^0_ b \rightarrow \left(\Lambda \pi ^+ \right)_{\Lambda ^+_ c }\pi ^- $ control mode and (right) $\Lambda \pi ^+ \pi ^- $ signal final states, for all subsamples combined. Superimposed on the data are the total result of the fit as a solid blue line, the $\Lambda ^0_ b $ ( $\Xi ^0_ b $ ) decay as a short-dashed black (double dot-dashed grey) line, cross-feed as triple dot-dashed brown lines, the combinatorial background as a long-dashed green line, and partially reconstructed background components with either a missing neutral pion as a dot-dashed purple line or a missing soft photon as a dotted cyan line.	Lb2LcL[..].pdf [19 KiB] HiDef png [263 KiB] Thumbnail [188 KiB] *.C file
	Lb2Lzp[..].pdf [21 KiB] HiDef png [289 KiB] Thumbnail [206 KiB] *.C file
Results of the fit for the (left) $\Lambda K ^\pm \pi ^\mp $ and (right) $\Lambda K ^+ K ^- $ final states, for all subsamples combined. Superimposed on the data are the total result of the fit as a solid blue line, the $\Lambda ^0_ b $ ( $\Xi ^0_ b $ ) decay as a short-dashed black (double dot-dashed grey) line, cross-feed as triple dot-dashed brown lines, the combinatorial background as a long-dashed green line, and partially reconstructed background components with either a missing neutral pion as a dot-dashed purple line or a missing soft photon as a dotted cyan line.	Lb2LzK[..].pdf [23 KiB] HiDef png [319 KiB] Thumbnail [235 KiB] *.C file
	Lb2LzK[..].pdf [22 KiB] HiDef png [300 KiB] Thumbnail [217 KiB] *.C file
Background-subtracted and efficiency-corrected Dalitz plot distributions for (left) $\Lambda ^0_ b \rightarrow \Lambda K ^+ \pi ^- $ and (right) $\Lambda ^0_ b \rightarrow \Lambda K ^+ K ^- $ with data from all subsamples combined. Boxes with a cross indicate negative values.	Kpi-DP[..].pdf [19 KiB] HiDef png [119 KiB] Thumbnail [66 KiB] *.C file
	KK-DP-[..].pdf [17 KiB] HiDef png [102 KiB] Thumbnail [60 KiB] *.C file
Animated gif made out of all figures.	PAPER-2016-004.gif Thumbnail

Tables and captions

Signal yields for the $\Lambda ^0_ b $ and $\Xi ^0_ b $ decay modes under investigation. The totals are simple sums and are not used in the analysis.	Table_1.pdf [68 KiB] HiDef png [107 KiB] Thumbnail [53 KiB] tex code
Systematic uncertainties (in units of $10^{-3}$) on the branching fraction ratios reported in Sec. 6. The total is the sum in quadrature of all contributions.	Table_2.pdf [53 KiB] HiDef png [44 KiB] Thumbnail [20 KiB] tex code
Systematic uncertainties on ${\cal A}_{ C P }$ (in units of $10^{-3}$).	Table_3.pdf [53 KiB] HiDef png [37 KiB] Thumbnail [17 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [523 KiB]
This ZIP file contains supplementary material for the publication LHCb-PAPER-2016-004. The files are: Supplementary.pdf : An overview of the extra figures .pdf, .png, *.eps : The figures in variuous formats	Fig1a-S.pdf [20 KiB] HiDef png [295 KiB] Thumbnail [225 KiB] *C file
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